Constant velocity joints (CVJ joints) and other rotational joints are common components in automotive vehicles. Typically, constant velocity joints are used where a transmission of constant velocity rotating motion is required. The common types of constant velocity joints are plunging tripod, a fixed tripod, a plunging ball joint and a fixed ball joint. These types of joints are currently used in front wheel drive vehicles, rear wheel drive vehicles and on propeller shafts found in rear wheel drive, all wheel drive, and four wheel drive vehicles. The constant velocity joints are generally grease lubricated for life and sealed by a sealing boot when used on driveshafts or half shafts. Therefore, constant velocity joints are sealed in order to retain grease inside the joint and keep contaminants, such as dirt and water, out of the joint. To achieve this protection the constant velocity joint is usually enclosed at the opened end of an outer race by a sealing boot made of a rubber, thermoplastic, or silicone type material. The opposite end of the outer race generally is enclosed by a dome or cap, known as a grease cap in the case of a disk type joint. A mono block or integral stem and race design style joint is sealed by the internal geometry of the outer race. This sealing and protection of the constant velocity joint is necessary because contamination of the inner chamber of the joint generally will cause internal damage to the joint.
A main function of the constant velocity joint is the transmission of rotational forces and torque. A plunging joint will transmit rotational velocity while permitting relative axial displacement within the joint. Generally, a tripod joint operates as a plunging constant velocity joint while providing some degree of axial articulation. In typical joint assemblies, a variety of bolted joint designs are used to assemble a joint to a propshaft or halfshaft within the automotive vehicle. These propshaft and halfshaft assemblies are typically assembled prior to installation within a driveline of a vehicle.
When a joint is installed within a vehicle, an inner rotating component is generally plunged further into the joint in order to fit between vehicle components, e.g., a propshaft and differential. Accordingly, some extra amount of plunge capability beyond that which is necessary during ordinary operation of the vehicle must necessarily be designed into the joint. However, as the amount of lubricant required for the joint is generally dictated in part by the surface area presented by an outer rotating member within the sealed portion of the joint, the provision of this extra plunge capability requires additional lubricant within the joint, increasing costs and failure modes during operation.
Accordingly, there is a need in the art for an improved constant velocity joint that offers adequate plunge capability to facilitate installation in a vehicle while minimizing the amount of lubricant needed within the joint.